When the sun goes down, hikers follow the trails to Mt. Hollywood, Mt. Bell and other spots for a heart-pounding yet serene workout unlike any other.

For me, the thrill of L.A.'s night life has nothing to do with A-list parties at Soho House and everything to do with dusty tracks and coyote calls. Twice a week for the last 25 years, I have been placing my feet along well-pummeled routes in Griffith Park right about the time most people are settling onto the couch to watch "Jeopardy!"

Even blindfolded on a dark night, I could make my way up trails nicknamed Razor Back and Cardiac Hill for their challenging terrain. The pitch of the trail, the occasional rocky chute to climb and the whiffs of sage and eucalyptus would easily guide me along the roughly 21/2-mile uphill route to the top of Mt. Hollywood, where thousands of pulsing lights create an indelible 360-degree snapshot of L.A. after dark. The Valley on one side, the Basin on the other; I can pick out orange ribbons of freeway, slashing across an otherwise orderly grid of streets, and downtown high-rises huddled on a seemingly endless horizon.

Hiking at night in Griffith Park is an open secret: Those who discover it become hopelessly addicted. I am forever dragging potential converts along with me, hoping to hook them with the lure of astonishing city views and a heart-pounding workout. Over time, the park has become my personal outdoor gym, my dirt treadmill, my trail time to catch up with friends.

"Life seems healthier and slower-paced in this nearby wilderness," writes my hiking buddy Mike Eberts, a professor at Glendale Community College who wrote the book "Griffith Park: A Centennial History." "Twigs, not tempers, snap here. It's quite a contrast from a surrounding city that often seems tense, dense, polluted and pooped."

On most weeknights around 7, new and avid hikers start from the Merry-Go-Round parking lot and begin the haul up fire roads and footpaths that lead straight into L.A.'s wild heart. Some go on conditioning hikes led by the Sierra Club or MeetUp.com, others (like me) go just with a buddy or two. The ever-burning lights of the city, especially when accompanied by a full moon, preclude any need for a flashlight. Mt. Hollywood by far is the most popular destination for night hikers, though some choose other routes to nearby Mt. Bell or Mt. Chapel. By the end of the night, I will have covered five miles and about 1,000 feet of gain in roughly two hours.

My favorite trail starts from the site of the Old L.A. Zoo and is officially labeled the Bill Eckert Trail on maps of the park (which no one really carries). At this time of year, lizards skitter along a path lined with creamy orange monkeyflowers, red larkspur, fuzzy-topped buckwheat and clusters of blue elderberries, all still visible in the waning light. Occasionally I've shared the trail with a tarantula or rattlesnake, and I usually hear coyotes yipping in the distance.

Dusk falls, the temperature drops a little and I settle into a steady uphill pace as aerial views of Glendale and Burbank emerge below. The din of the city is a muted hum, creating the illusion of being far away while standing smack in L.A.'s urban center.

About a mile up a steady calf-burning incline, the trail leads to Water Tower 113, where there's a convenient water fountain and an oddly placed cement staircase, presumably there for the maintenance workers. It leads to the paved Vista Del Valle Drive, an old road long ago placed off-limits to cars. I go up a short stretch of the road's buckled asphalt surface and then turn left to do battle with Cardiac Hill.

This steep slog on a fire road is the toughest part of the route and a great place to people-watch. Those who know it and are used to its rigors confidently hit their stride, while newcomers hopefully scan each twist and turn for any hint of an end to the grind. It's not all that long, maybe less than a quarter mile, but it is unrelenting. (Farther along Vista Del Valle there's a gentler route called Cardiac Bypass that's slightly longer but easier on the pulse.)

At the top of the hill, it's a hard left onto the Mt. Hollywood Trail, then 10 minutes along a more gentle rise that takes you the last half-mile to the top. There are other ways to get here, but I prefer this route for the extraordinary views you get to the north as you climb: the wall of mountains formed by the Verdugos and the San Gabriels.

At the summit, tuckered-out kids stagger to grab a spot at a couple of picnic tables at the very top; teen couples hold hands and gawk at the view of the L.A. Basin. Look in any direction and you see glittery icons of L.A.: the Griffith Observatory immediately below, the Capitol Records Building in Hollywood off to the right and the Hollywood sign on Mt. Lee to the west. Sometimes you can hear strains of music coming from a concert at the Greek Theatre.

Many times I've stood on this summit completely alone, struck by the notion of being the only one of 4 million people in the city who decided to take a hike that night.

But usually I have plenty of company — close friends I have met on these hills over the years (one of whom I married) and longtime leaders who cheer on their charges as they make their way up the trail. Among the folks who gather here, there's a kind of giddiness, a shared glee in knowing that we're among a small percentage of Angelenos who have successfully made the pilgrimage — and that we'll be back.